The movie Resolution is 3640x1020px. in 60FPS. I encoded it in HAP but the movie stutters from time to time
For such high res + HAP, the operation is complex, kinda heavy for your computer's CPU.
When I re-encode or export huge movies files from my editing software I close all the other programs and wait until the export / re-encode is done.
Otherwise, if I'm doing anything else, I can be sure that the resulting movie file will stutter from time to time
Try again with nothing else than your encoding HAP operating
Try a different FPS setting as well